Direct Connection of Supercapacitor–Battery Hybrid Storage System to the Grid-Tied Photovoltaic System

Abstract

Penetration rate of grid-connected photovoltaic (PV) generation to the existing utility grid is rapidly increasing over the years. Since the power generated from PV systems fluctuates according to the weather condition, e.g., cloud passing, this can significantly disturb the stability of a weak utility grid. The integration of energy storage devices and its ramp-rate control technique are required to reduce the impact of PV systems output fluctuations and augment the stability of the utility grid. In this paper, ramp-rate control is applied to the direct connection of energy storage devices in PV generation system configuration. The direct connection of supercapacitors string and battery combination scheme is proposed to reduce the number of power converters so that the efficiency of the system is increased. In this work, the PV system output is controlled by directly controlling the energy storage system (ESS) to limit the changing rate of the PV output to a desired ramp-rate value, hence reducing the battery charge/discharge cycles and extending the expected lifetime of the ESS. The performance of the proposed direct connection scheme of the ESS and its ramp-rate control strategy is verified using a 1-kW PV system prototype.

Performance evaluation of online open-circuit voltage estimation method for photovoltaic system

“…The I p and I d is determined from Eqs. (7) and (9), respectively. The addition of I ph , I pv , and I d gives the I p value.…”

“…To cope with the aforesaid problems, a pilot cell can be used [7,8], however, during the mismatch of irradiance between pilot cell and main PV panel, pilot cell gives the wrong value of V oc [9]. In [10], a semi pilot cell is presented in which one cell of PV panel is used for V oc measurement, but power loss (1.8%) occurs due to this single cell.…”

New types of hybrid electrolytes for supercapacitors

“…They can also be used as capacity compensation and recovery in starting and braking motor vehicles. In addition, SCs can also efficiently store photovoltaic power and wind power in the power generation mode to achieve grid-connected power generation [11][12][13][14][15].…”

Energy management strategy with two degrees of freedom for hybrid energy storage systems in islanded DC microgrids

“…Therefore, various energy storages with different characteristics are combined to form the hybrid ESS (HESS). Among different configurations of HESS, the combination of the supercapacitor (SC) and the battery is the most mainstream [7]. In Fig.…”